Liquid crystal composition and liquid crystal display device

ABSTRACT

The invention is to provide a liquid crystal composition that satisfies at least one of characteristics such as a high maximum temperature of a nematic phase, a low minimum temperature of a nematic phase, a small viscosity, a suitable optical anisotropy, a large negative dielectric anisotropy, a large specific resistance, a high stability to ultraviolet light and a high stability to heat, or that is suitably balanced regarding at least two of the characteristics, wherein the liquid crystal composition has negative dielectric anisotropy and includes a specific compound having a large negative dielectric anisotropy as a first component, a specific compound containing a pyran ring and having a large negative dielectric anisotropy as a second component, a specific compound having a small viscosity as a third component, and a specific compound having a large negative dielectric anisotropy as a fourth component, and the liquid crystal display device contains this composition.

FIELD OF THE INVENTION

The invention relates mainly to a liquid crystal composition suitablefor use in an active matrix (AM) device and so forth, and an AM deviceand so forth that contains the composition. More specifically, theinvention relates to a liquid crystal composition having negativedielectric anisotropy, and a device containing the composition andhaving a mode such as in-plane switching (IPS), vertical alignment (VA)or polymer sustained alignment (PSA).

BACKGROUND OF THE INVENTION

In a liquid crystal display device, a classification based on anoperating mode for liquid crystals includes phase change (PC), twistednematic (TN), super twisted nematic (STN), electrically controlledbirefringence (ECB), optically compensated bend (OCB), in-planeswitching (IPS), vertical alignment (VA) and polymer sustained alignment(PSA). A classification based on a driving mode in the device includes apassive matrix (PM) and an active matrix (AM). The PM is furtherclassified into static, multiplex and so forth, and the AM is classifiedinto a thin film transistor (TFT), a metal-insulator-metal (MIM) and soforth. The TFT is further classified into amorphous silicon andpolycrystal silicon. The latter is classified into a high temperaturetype and a low temperature type according to the production process. Aclassification based on a light source includes a reflection typeutilizing natural light, a transmission type utilizing a backlight and asemi-transmission type utilizing both natural light and a backlight.

These devices contain a liquid crystal composition having suitablecharacteristics. The liquid crystal composition has a nematic phase.General characteristics of the composition should be improved to give anAM device having good general characteristics. Table 1 below summarizesthe relationship between the general characteristics of the two. Thegeneral characteristics of the composition will be explained furtherbased on a commercially available AM device. The temperature range of anematic phase relates to the temperature range in which the device canbe used. A desirable maximum temperature of the nematic phase is 70° C.or higher and a desirable minimum temperature of the nematic phase is−10° C. or lower. The viscosity of the composition relates to theresponse time of the device. A short response time is desirable fordisplaying moving images on the device. Accordingly, a small viscosityof the composition is desirable. A small viscosity at a low temperatureis more desirable.

TABLE 1 General Characteristics of Composition and AM Device GeneralCharacteristics General Characteristics No. of Composition of AM Device1 wide temperature range wide usable temperature of a nematic phaserange 2 small viscosity ¹⁾ short response time 3 suitable optical largecontrast ratio anisotropy 4 large positive or negative low thresholdvoltage and dielectric anisotropy small electric power consumption largecontrast ratio 5 large specific resistance large voltage holding ratioand large contrast ratio 6 high stability to ultraviolet long servicelife light and heat ¹⁾ A liquid crystal composition can be injected intoa liquid crystal cell in a shorter period of time.

The optical anisotropy of the composition relates to the contrast ratioof the device. The product (Δn×d) of the optical anisotropy (Δn) of thecomposition and the cell gap (d) of the device is designed so as tomaximize the contrast ratio. A suitable value of the product depends onthe kind of operating mode. In a device having a VA mode, a suitablevalue is in the range of 0.30 μm to 0.40 μm, and in a device having anIPS mode, a suitable value is in the range of 0.20 μm to 0.30 μm. Inthis case, a composition having a large optical anisotropy is desirablefor a device having a small cell gap. A large absolute value of thedielectric anisotropy in the composition contributes to a low thresholdvoltage, small electric power consumption and a high contrast ratio ofthe device. Accordingly, a large absolute value of the dielectricanisotropy is desirable. A large specific resistance of the compositioncontributes to a large voltage holding ratio and a large contrast ratioof the device. Accordingly, a composition having a large specificresistance is desirable at room temperature and also at a hightemperature in the initial stage. A composition having a large specificresistance is desirable at room temperature and also at a hightemperature after it has been used for a long time. The stability of thecomposition to ultraviolet light and heat relates to the service life ofthe liquid crystal display device. In the case where the stability ishigh, the device has a long service life. Such characteristics aredesirable for an AM device used in a liquid crystal projector, a liquidcrystal television and so forth.

A composition having positive dielectric anisotropy is used for an AMdevice having a TN mode. On the other hand, a composition havingnegative dielectric anisotropy is used for an AM device having a VAmode. A composition having positive or negative dielectric anisotropy isused for an AM device having an IPS mode. A composition having positiveor negative dielectric anisotropy is used for an AM device having a PSAmode. Examples of the liquid crystal composition having negativedielectric anisotropy are disclosed in the following patent documentsNo. 1 to No. 3.

PRIOR ART Patent Document

-   Patent document No. 1: JP 2006-160857 A.-   Patent document No. 2: JP 2006-160727 A.-   Patent document No. 3: JP H10-291945 A (1998).

A desirable AM device has characteristics such as a wide temperaturerange in which the device can be used, a short response time, a largecontrast ratio, a low threshold voltage, a large voltage holding ratioand a long service life. Response time that is even one millisecondshorter than that of the other devices is desirable. Thus, desirablecharacteristics of the composition include a high maximum temperature ofa nematic phase, a low minimum temperature of a nematic phase, a smallviscosity, a suitable optical anisotropy, a large positive or negativedielectric anisotropy, a large specific resistance, a high stability toultraviolet light and a high stability to heat.

OUTLINE OF THE INVENTION Subject to be Solved by the Invention

One of the aims of the invention is to provide a liquid crystalcomposition that satisfies at least one of characteristics such as ahigh maximum temperature of a nematic phase, a low minimum temperatureof a nematic phase, a small viscosity, a suitable optical anisotropy, alarge negative dielectric anisotropy, a large specific resistance, ahigh stability to ultraviolet light and a high stability to heat.Another aim is to provide a liquid crystal composition that is suitablybalanced regarding at least two of the characteristics. A further aim isto provide a liquid crystal display device that contains such acomposition. An additional aim is to provide a liquid crystalcomposition that has a suitable optical anisotropy which means a largeoptical anisotropy or a small optical anisotropy, a large negativedielectric anisotropy, a high stability to ultraviolet light and soforth, and is to provide an AM device that has a short response time, alarge voltage holding ratio, a large contrast ratio, a long service lifeand so forth.

Means for Solving the Subject

The invention concerns a liquid crystal composition that includes atleast one compound selected from the group of compounds represented byformula (1) as a first component and at least one compound selected fromthe group of compounds represented by formula (2) as a second component:

wherein R¹, R², R³ and R⁴ are independently alkyl having 1 to 12carbons, alkoxy having 1 to 12 carbons, alkenyl having 2 to 12 carbons,alkenyloxy having 2 to 11 carbons, or alkenyl having 2 to 12 carbons inwhich arbitrary hydrogen is replaced by fluorine; ring A and ring B areeach independently 1,4-cyclohexylene, 1,4-phenylene,2-fluoro-1,4-phenylene, or 3-fluoro-1,4-phenylene; ring C isindependently

at least one of ring C is

X¹, X², X³ and X⁴ are independently fluorine or chlorine; Z¹ and Z² areindependently a single bond, ethylene, methyleneoxy or carbonyloxy; andm is 0, 1 or 2; n is 1 or 2.

Effect of the Invention

An advantage of the invention is a liquid crystal composition thatsatisfies at least one of characteristics such as a high maximumtemperature of a nematic phase, a low minimum temperature of a nematicphase, a small viscosity, a suitable optical anisotropy, a largenegative dielectric anisotropy, a large specific resistance, a highstability to ultraviolet light and a high stability to heat. One aspectof the invention is a liquid crystal composition that is suitablybalanced regarding at least two of the characteristics. Another aspectis a liquid crystal display device that contains such a composition. Afurther aspect is a composition that has a suitable optical anisotropy,a large negative dielectric anisotropy, a high stability to ultravioletlight and so forth, and an AM device that has a short response time, alarge voltage holding ratio, a large contrast ratio, a long service lifeand so forth.

EMBODIMENT TO CARRY OUT THE INVENTION

Usage of the terms in the specification and claims is as follows. Theliquid crystal composition of the invention and the liquid crystaldisplay device of the invention may be abbreviated to “the composition”and “the device,” respectively. “A liquid crystal display device” is ageneric term for a liquid crystal display panel and a liquid crystaldisplay module. “A liquid crystal compound” is a generic term for acompound having a liquid crystal phase such as a nematic phase or asmectic phase, and also for a compound having no liquid crystal phasesbut being useful as a component of a composition. Such a useful compoundhas a six-membered ring such as 1,4-cyclohexylene and 1,4-phenylene, anda rod-like molecular structure. An optically active compound and apolymerizable compound may occasionally be added to the composition.Even in the case where these compounds are liquid crystalline, thecompounds are classified as an additive herein. At least one compoundselected from the group of compounds represented by formula (1) may beabbreviated to “the compound (1).” “The compound (1)” means onecompound, or two or more compounds represented by formula (1). The samerules apply to compounds represented by the other formulas. “Arbitrary”is used not only in cases where the position is arbitrary but also incases where the number is arbitrary. However, it is not used in caseswhere the number is 0 (zero).

A higher limit of the temperature range of a nematic phase may beabbreviated to “the maximum temperature.” A lower limit of thetemperature range of a nematic phase may be abbreviated to “the minimumtemperature.” That “specific resistance is large” means that acomposition has a large specific resistance at room temperature and alsoat a temperature close to the maximum temperature of a nematic phase inthe initial stage, and that the composition has a large specificresistance at room temperature and also at a temperature close to themaximum temperature of a nematic phase even after it has been used for along time. That “a voltage holding ratio is large” means that a devicehas a large voltage holding ratio at room temperature and also at atemperature close to the maximum temperature of a nematic phase in theinitial stage, and that the device has a large voltage holding ratio atroom temperature and also at a temperature close to the maximumtemperature of a nematic phase even after it has been used for a longtime. When characteristics such as optical anisotropy are explained,values which are obtained according to the measuring methods describedin Examples will be used. A first component means one compound, or twoor more compounds. “The ratio of the first component” is expressed as apercentage by weight (% by weight) of the first component based on thetotal weight of the liquid crystal composition. The same rule applies tothe ratio of a second component and so forth. The ratio of an additivemixed with the composition is expressed as a percentage by weight (% byweight) or weight parts per million (ppm) based on the total weight ofthe liquid crystal composition.

The symbol R¹ is used for a plurality of compounds in the chemicalformulas of component compounds. The meanings of R¹ may be the same ordifferent in two arbitrary compounds among these. In one case, forexample, R¹ of the compound (1) is ethyl and R¹ of the compound (1-1) isethyl. In another case, R¹ of the compound (1) is ethyl and R¹ of thecompound (1-1) is propyl. The same rule applies to the symbols R², R³and so forth.

The invention includes the following items.

1. A liquid crystal composition that includes at least one compoundselected from the group of compounds represented by formula (1) as afirst component and at least one compound selected from the group ofcompounds represented by formula (2) as a second component:

wherein R¹, R², R³ and R⁴ are independently alkyl having 1 to 12carbons, alkoxy having 1 to 12 carbons, alkenyl having 2 to 12 carbons,alkenyloxy having 2 to 11 carbons, or alkenyl having 2 to 12 carbons inwhich arbitrary hydrogen is replaced by fluorine; ring A and ring B areeach independently 1,4-cyclohexylene, 1,4-phenylene,2-fluoro-1,4-phenylene, or 3-fluoro-1,4-phenylene; ring C isindependently

at least one of ring C is

X¹, X², X³ and X⁴ are independently fluorine or chlorine; Z¹ and Z² areindependently a single bond, ethylene, methyleneoxy or carbonyloxy; andm is 0, 1 or 2; n is 1 or 2.2. The liquid crystal composition according to item 1, wherein the firstcomponent is at least one compound selected from the group of compoundsrepresented by formula (1-1) and formula (1-2):

wherein R¹ and R² are independently alkyl having 1 to 12 carbons, alkoxyhaving 1 to 12 carbons, alkenyl having 2 to 12 carbons, alkenyloxyhaving 2 to 11 carbons, or alkenyl having 2 to 12 carbons in whicharbitrary hydrogen is replaced by fluorine; ring B is independently1,4-cyclohexylene, 1,4-phenylene, 2-fluoro-1,4-phenylene, or3-fluoro-1,4-phenylene; X¹ and X² are independently fluorine orchlorine; Z³ is independently a single bond, ethylene or methyleneoxy.3. The liquid crystal composition according to item 2, wherein the firstcomponent is at least one compound selected from the group of compoundsrepresented by formula (1-2).4. The liquid crystal composition according to item 2, wherein the firstcomponent is a mixture of at least one compound selected from the groupof compounds represented by formula (1-1) and at least one compoundselected from the group of compounds represented by formula (1-2).5. The liquid crystal composition according to any one of items 1 to 4,wherein the second component is at least one compound selected from thegroup of compounds represented by formula (2-1) to formula (2-7):

wherein R³ and R⁴ are independently alkyl having 1 to 12 carbons, alkoxyhaving 1 to 12 carbons, alkenyl having 2 to 12 carbons, alkenyloxyhaving 2 to 11 carbons, or alkenyl having 2 to 12 carbons in whicharbitrary hydrogen is replaced by fluorine.6. The liquid crystal composition according to item 5, wherein thesecond component is at least one compound selected from the group ofcompounds represented by formula (2-1) to formula (2-3)'.7. The liquid crystal composition according to item 5, wherein thesecond component is at least one compound selected from the group ofcompounds represented by formula (2-4) to formula (2-7).8. The liquid crystal composition according to any one of items 1 to 7,wherein the ratio of the first component is in the range of 5% by weightto 70% by weight and the ratio of the second component is in the rangeof 5% by weight to 60% by weight, based on the total weight of theliquid crystal composition.9. The liquid crystal composition according to any one of items 1 to 8,further including at least one compound selected from the group ofcompounds represented by formula (3) as a third component:

wherein R⁵ and R⁶ are independently alkyl having 1 to 12 carbons, alkoxyhaving 1 to 12 carbons, alkenyl having 2 to 12 carbons, or alkenylhaving 2 to 12 carbons in which arbitrary hydrogen is replaced byfluorine; ring D and the ring E are independently 1,4-cyclohexylene,1,4-phenylene, 2-fluoro-1,4-phenylene or 3-fluoro-1,4-phenylene; Z⁴ isindependently a single bond, ethylene, methyleneoxy or carbonyloxy; andp is 1, 2 or 3.10. The liquid crystal composition according to item 9, wherein thethird component is at least one compound selected from the group ofcompounds represented by formula (3-1) to formula (3-12):

wherein R⁵ and R⁶ are independently alkyl having 1 to 12 carbons, alkoxyhaving 1 to 12 carbons, alkenyl having 2 to 12 carbons, or alkenylhaving 2 to 12 carbons in which arbitrary hydrogen is replaced byfluorine.11. The liquid crystal composition according to item 10, wherein thethird component is at least one compound selected from the group ofcompounds represented by formula (3-1).12. The liquid crystal composition according to item 10, wherein thethird component is a mixture of at least one compound selected from thegroup of compounds represented by formula (3-1) and at least onecompound selected from the group of compounds represented by formula(3-4).13. The liquid crystal composition according to item 10, wherein thethird component is a mixture of at least one compound selected from thegroup of compounds represented by formula (3-6) and at least onecompound selected from the group of compounds represented by formula(3-12).14. The liquid crystal composition according to any one of items 9 to13, wherein the ratio of the third component is in the range of 10% byweight to 75% by weight based on the total weight of the liquid crystalcomposition.15. The liquid crystal composition according to any one of items 1 to14, further including at least one compound selected from the group ofcompounds represented by formula (4-1) and (4-2) as a fourth component:

wherein R⁷ and R⁸ are independently alkyl having 1 to 12 carbons, alkoxyhaving 1 to 12 carbons, alkenyl having 2 to 12 carbons, or alkenylhaving 2 to 12 carbons in which arbitrary hydrogen is replaced byfluorine; the ring F and ring G are each independently 1,4-cyclohexyleneor 1,4-phenylene; Z⁵, Z⁶ and Z⁷ are each independently a single bond,ethylene, methyleneoxy or carbonyloxy; X⁵ and X⁶ are independentlyfluorine or chlorine; and q is 1, 2 or 3; r and s are each independently0, 1, 2 or 3, and the sum of r and s is 3 or less.16. The liquid crystal composition according to item 15, wherein thefourth component is at least one compound selected from the group ofcompounds represented by formula (4-1-1) to formula (4-1-9) and formula(4-2-1) to (4-2-5):

wherein R⁷ and R⁸ are independently alkyl having 1 to 12 carbons, alkoxyhaving 1 to 12 carbons, alkenyl having 2 to 12 carbons, or alkenylhaving 2 to 12 carbons in which arbitrary hydrogen is replaced byfluorine.

17. The liquid crystal composition according to item 16, wherein thefourth component is at least one compound selected from the group ofcompounds represented by formula (4-1-1).18. The liquid crystal composition according to item 16, wherein thefourth component is a mixture of at least one compound selected from thegroup of compounds represented by formula (4-1-1) and at least onecompound selected from the group of compounds represented by formula(4-1-7).19. The liquid crystal composition according to any one of items 15 to18, wherein the ratio of fourth component is 5% to 60% by weight basedon the total weight of the liquid crystal composition.20. The liquid crystal composition according to any one of items 1 to19, wherein the maximum temperature of a nematic phase is 70° C. orhigher, the optical anisotropy (25° C.) at a wavelength of 589nanometers is 0.08 or more, and the dielectric anisotropy (25° C.) at afrequency of 1 kHz is −2 or less.21. A liquid crystal display device containing the liquid crystalcomposition according to any one of items 1 to 20.22. The liquid crystal display device according to item 21, wherein anoperating mode of the liquid crystal display device is a VA mode, an IPSmode or a PSA mode, and a driving mode of the liquid crystal displaydevice is an active matrix mode.

The invention further includes the following items: (1) the compositiondescribed above that further includes an optically active compound; (2)the composition described above that further includes an additive, suchas an antioxidant, an ultraviolet light absorber and an antifoamingagent; (3) an AM device that contains the composition described above;(4) a device having a mode of TN, ECB, OCB, IPS, VA or PSA andcontaining the composition described above; (5) a transmission-typedevice that contains the composition described above; (6) use of thecomposition described above as a composition having a nematic phase; and(7) use of an optically active composition prepared by the addition ofan optically active compound to the composition described above.

The composition of the invention will be explained in the followingorder. First, the constitution of component compounds in the compositionwill be explained. Second, main characteristics of the componentcompounds and main effects of these compounds on the composition will beexplained. Third, a combination of components in the composition,desirable ratios of the component compounds and the basis thereof willbe explained. Fourth, a desirable embodiment of the component compoundswill be explained. Fifth, specific examples of the component compoundswill be shown. Sixth, additives that may be mixed with the compositionwill be explained. Seventh, methods for synthesizing the componentcompounds will be explained. Last, use of the composition will beexplained.

First, the constitution of component compounds in the composition willbe explained. The compositions of the invention are classified into thecomposition A and the composition B. The composition A may furtherinclude any other liquid crystal compound, an additive and an impurity.“Any other liquid crystal compound” is a liquid crystal compound that isdifferent from the compound (1), the compound (2), the compound (3) andthe compound (4). Such a compound is mixed with the composition for thepurpose of further adjusting characteristics of the composition. Of anyother liquid crystal compound, a smaller amount of a cyano compound isdesirable in view of its stability to heat or ultraviolet light. A moredesirable ratio of the cyano compound is 0% by weight. The additiveincludes an optically active compound, an antioxidant, an ultravioletlight absorber, a coloring matter, an antifoaming agent, a polymerizablecompound and a polymerization initiator. The impurity is compounds andso forth which have contaminated component compounds in a process suchas their synthesis. Even in the case where the compound is liquidcrystalline, it is classified into the impurity herein.

The composition B consists essentially of compounds selected from thegroup of the compound (1), the compound (2), the compound (3), thecompound (4-1) and the compound (4-2). The term “essentially” means thatthe composition may include an additive and an impurity, but does notinclude any liquid crystal compound other than these compounds. Thecomposition B has a smaller number of components than the composition A.The composition B is preferable to the composition A in view of costreduction. The composition A is preferable to the composition B in viewof the fact that physical properties can be further adjusted by addingother liquid crystal compound.

Second, main characteristics of the component compounds and main effectsof the compounds on the characteristics of the composition will beexplained. The main characteristics of the component compounds aresummarized in Table 2 on the basis of the effects of the invention. InTable 2, the symbol L stands for “large” or “high”, the symbol M standsfor “medium”, and the symbol S stands for “small” or “low.” The symbolsL, M and S are classified according to a qualitative comparison amongthe component compounds, and 0 (zero) means that “a value is nearlyzero.”

TABLE 2 Characteristics of Compounds Compounds Compound (1) Compound (2)Compound (3) Compound (4) Maximum M S-M M-L M-L Temperature ViscosityM-L M S-M M-L Optical Anisotropy M M-L S-L M-L Dielectric Anisotropy M-L¹⁾ M-L ¹⁾ 0 M ¹⁾ Specific Resistance L L L L ¹⁾ Value of opticalanisotropy is negative, and the symbol expresses the magnitude of theabsolute value. Compounds Compounds Compound (1) Compound (2) Compound(3) (4-1) (4-2) Maximum M-L S-M S-L M-L temperature Viscosity M-L S-LS-M M-L Optical anisotropy M-L M-L S-M M-L Dielectric anisotropy M-L ¹⁾M-L ¹⁾ 0 M-L ¹⁾ Specific resistance L L L L ¹⁾ Value of Dielectricanisotropy is negative, and the symbol expresses the magnitude of theabsolute value.

Main effects of the component compounds on the characteristics of thecomposition upon mixing the component compounds with the composition areas follows. The compound (1) increases the absolute value of thedielectric anisotropy, and increases the optical anisotropy. Thecompound (2) increases the absolute value of the dielectric anisotropy.The compound (3) decreases the viscosity, adjusts the optical anisotropysuitably, increases the maximum temperature, and decreases the minimumtemperature. The compounds (4-1) and (4-2) increase the absolute valueof the dielectric anisotropy, and decreases the minimum temperature.

Third, a combination of the components in the composition, desirableratios of the component compounds and the basis thereof will beexplained. A combination of the components in the composition is thefirst and second components, the first, second and third components, thefirst, second and fourth components and the first, second, third andfourth components.

A desirable combination of the components in the composition is thefirst and second components for increasing the absolute value ofdielectric anisotropy, the first, second and third components fordecreasing the viscosity or for increasing the maximum temperature, andthe first, second, third and fourth components for increasing theabsolute value of dielectric anisotropy, or for increasing the maximumtemperature.

A desirable ratio of the first component is 5% by weight or more forincreasing the absolute value of the dielectric anisotropy, and 70% byweight or less for decreasing the minimum temperature. A more desirableratio is in the range of 10% by weight to 40% by weight. An especiallydesirable ratio is in the range of 10% by weight to 30% by weight.

A desirable ratio of the second component is 5% by weight or more fordecreasing the viscosity and 60% by weight or less for increasing themaximum temperature. Amore desirable ratio is in the range of 10% byweight to 30% by weight for decreasing the viscosity.

A desirable ratio of the third component is 10% by weight or more fordecreasing the viscosity and 75% by weight or less for decreasing theminimum temperature. Amore desirable ratio is in the range of 20% byweight to 60% by weight. An especially desirable ratio is in the rangeof 40% by weight to 60% by weight.

A desirable ratio of the fourth component is 5% by weight or more forincreasing the absolute value of the dielectric anisotropy and 60% byweight or less for decreasing the minimum temperature. A more desirableratio is in the range of 5% by weight to 40% by weight. An especiallydesirable ratio is in the range of 20% by weight to 35% by weight.

Fourth, a desirable embodiment of the component compounds will beexplained. R¹, R², R³ and R⁴ are independently alkyl having 1 to 12carbons, alkoxy having 1 to 12 carbons, alkenyl having 2 to 12 carbons,alkenyloxy having 2 to 11 carbons, or alkenyl having 2 to 12 carbons inwhich arbitrary hydrogen is replaced by fluorine, and R⁵, R⁶, R⁷ and R⁸are independently alkyl having 1 to 12 carbons, alkoxy having 1 to 12carbons, alkenyl having 2 to 12 carbons, or alkenyl having 2 to 12carbons in which arbitrary hydrogen is replaced by fluorine.

Desirable R¹, R², R³, R⁴, R⁷ or R⁸ is alkyl having 1 to 12 carbons oralkenyl having 2 to 12 carbons for decreasing the minimum temperature orfor decreasing the viscosity, and alkoxy having 1 to 12 carbons forincreasing the absolute value of the dielectric anisotropy. Desirable R⁵or R⁶ is alkyl having 1 to 12 carbons or alkenyl having 2 to 12 carbonsor alkenyl having 2 to 12 carbons in which arbitrary hydrogen isreplaced by fluorine for decreasing the minimum temperature or fordecreasing the viscosity. More desirable R¹, R², R³, R⁴, R⁵, R⁶, R⁷ orR⁸ is alkyl having 1 to 12 carbons for increasing the stability toultraviolet light, heat or the like.

Desirable alkyl is methyl, ethyl, propyl, butyl, pentyl, hexyl, heptylor octyl. More desirable alkyl is ethyl, propyl, butyl, pentyl or heptylfor decreasing the viscosity.

Desirable alkoxy is methoxy, ethoxy, propoxy, butoxy, pentyloxy,hexyloxy or heptyloxy. More desirable alkoxy is methoxy or ethoxy fordecreasing the viscosity.

Desirable alkenyl is vinyl, 1-propenyl, 2-propenyl, 1-butenyl,2-butenyl, 3-butenyl, 1-pentenyl, 2-pentenyl, 3-pentenyl, 4-pentenyl,1-hexenyl, 2-hexenyl, 3-hexenyl, 4-hexenyl or 5-hexenyl. More desirablealkenyl is vinyl, 1-propenyl, 3-butenyl or 3-pentenyl for decreasing theviscosity. A desirable configuration of —CH═CH— in the alkenyl dependson the position of the double bond. Trans is preferable in the alkenylsuch as 1-propenyl, 1-butenyl, 1-pentenyl, 1-hexenyl, 3-pentenyl and3-hexenyl for decreasing the viscosity, for instance. Cis is preferablein the alkenyl such as 2-butenyl, 2-pentenyl and 2-hexenyl. In thealkenyl, straight-chain alkenyl is preferable to branched-chain alkenyl.

Desirable alkenyloxy is vinyloxy, allyloxy, 3-butenyloxy, 3-pentenyloxyor 4-pentenyloxy. More desirable alkenyloxy is allyloxy or 3-butenyloxyfor decreasing the viscosity.

Desirable examples of alkenyl in which arbitrary hydrogen is replaced byfluorine are 2,2-difluorovinyl, 3,3-difluoro-2-propenyl,4,4-difluoro-3-butenyl, 5,5-difluoro-4-pentenyl and6,6-difluoro-5-hexenyl. More desirable examples are 2,2-difluorovinyland 4,4-difluoro-3-butenyl for decreasing the viscosity.

The ring A, B, D and the ring E are independently 1,4-cyclohexylene or1,4-phenylene, 2-fluoro-1,4-phenylene or 3-fluoro-1,4-phenylene and therings B may be the same or different when m is 2, and arbitrary two ofthe ring D may be the same or different when p is 2 or 3. Desirable ringA, B, D or ring E is each 1,4-cyclohexylene for increasing the maximumtemperature or for decreasing the viscosity, and 1,4-phenylene forincreasing the optical anisotropy.

The ring C is

at least one ring C is

Two rings C may be the same or different when n is 2. Desirable ring Cis

for increasing the absolute value of dielectric anisotropy.

The ring F and the ring G are independently 1,4-cyclohexylene, or4-phenylene, arbitrary two of the ring F may be the same or differentwhen r is 2 or 3, and arbitrary two of the ring G may be the same ordifferent when s is 2 or 3. Desirable ring F or ring G is1,4-cyclohexylene for increasing the maximum temperature or fordecreasing the viscosity and 1,4-phenylene for increasing the opticalanisotropy.

X¹, X², X³ and X⁴ are independently fluorine or chlorine. Desirable X¹,X², X³ or X⁴ is fluorine for decreasing the viscosity. X⁵ and X⁶ areindependently fluorine or chlorine. Desirable X⁵ or X⁶ is fluorine fordecreasing the viscosity.

Z¹, Z², Z⁴, Z⁵, Z⁶ and Z⁷ are each independently a single bond,ethylene, methyleneoxy or carbonyloxy, and two of Z¹ may be the same ordifferent when m is 2, two of Z² may be the same or different when n is2, and two of Z⁴ may be the same or different when p is 2 or 3, two ofZ⁵ may be the same or different when q is 2 or 3, two of Z⁶ may be thesame or different when r is 2 or 3, and two of Z⁷ may be the same ordifferent when s is 2 or 3. Desirable Z¹, Z², Z⁴, Z⁵, Z⁶ or Z⁷ isindependently ethylene for decreasing the minimum temperature, and asingle bond for decreasing the viscosity. Z³ is a single bond, ethyleneor methyleneoxy. Desirable Z³ is a single bond for decreasing theviscosity, and methyleneoxy for increasing the absolute value ofdielectric anisotropy.

m is 0, 1 or 2. Desirable m is for 2 for increasing the maximumtemperature. n is 1 or 2. Desirable n is 2 for increasing the maximumtemperature, and 1 for decreasing the viscosity. p is 1, 2 or 3.Desirable p is 2 or 3 for increasing the maximum temperature, and is 1for decreasing the viscosity. q is 1, 2 or 3. Desirable p is 2 or 3 forincreasing the maximum temperature, and 1 for deceasing the viscosity. rand s are each independently 0, 1, 2 or 3, and the sum of r and s is 3or less. Desirable r or s is 2 or 3 for increasing the maximumtemperature, and r or s is 1 for decreasing the viscosity.

Fifth, specific examples of the component compounds will be shown. Inthe desirable compounds described below, X¹ and X² are independentlyfluorine or chlorine, R⁹ and R¹⁰ are independently straight-chain alkylhaving 1 to 12 carbons, alkoxy having 1 to 12 carbons, straight-chainalkenyl having 2 to 12 carbons and straight-chain alkenlyoxy having 2 to11 carbons, and R¹¹ and R¹² are independently straight-chain alkylhaving 1 to 12 carbons, alkoxy having 1 to 12 carbons and straight-chainalkenyl having 2 to 12 carbons. With regard to the configuration of1,4-cyclohexylene in these compounds, trans is preferable to cis forincreasing the maximum temperature.

Desirable compound (1) are the compound (1-1-1) to the compound (1-2-6).More desirable compound (1) are the compound (1-2-2), (1-2-3) and thecompound (1-2-6). Desirable compound (2) are the compound (2-1-1) to thecompound (2-7-1). More desirable compound (2) are the compound (2-4-1)to the compound (2-7-1). Especially desirable compound (2) are thecompound (2-4-1), (2-5-1) and the compound (2-7-1). Desirable compound(3) are the compound (3-1-1) to the compound (3-12-1). More desirablecompound (3) are the compound (3-1-1) to the compound (3-4-1) and thecompound (3-6-1) to the compound (3-12-1). Especially desirable compound(3) are the compound (3-1-1), (3-4-1), (3-6-1) and the compound(3-12-1). Desirable compound (4) are the compound (4-1-1-1) to thecompound (4-2-5-1). More desirable compound (4) are the compound(4-1-1-1) to the compound (4-1-7-1) and the compound (4-2-1-1) to thecompound (4-2-4-1). Especially desirable compound (4) are the compound(4-1-1-1), (4-1-2-1), (4-1-4-1), (4-1-6-1) and the compound (4-2-4-1).

Sixth, additives which may be mixed with the composition will beexplained. Such additives include an optically active compound, anantioxidant, an ultraviolet light absorber, a coloring matter, anantifoaming agent, a polymerizable compound and a polymerizationinitiator. The optically active compound is mixed with the compositionfor the purpose of inducing a helical structure and giving a twist anglein liquid crystals. Examples of such compounds include the compound(5-1) to the compound (5-4). A desirable ratio of the optically activecompound is 5% by weight or less, and a more desirable ratio is in therange of 0.01% by weight to 2% by weight.

An antioxidant is mixed with the composition in order to prevent adecrease in specific resistance that is caused by heating under air, orto maintain a large voltage holding ratio at room temperature and alsoat a high temperature after the device was used for a long time.

Desirable examples of the antioxidant include the compound (6) where wis an integer from 1 to 9. In the compound (6), desirable w is 1, 3, 5,7 or 9. More desirable w is 1 or 7. The compound (6) where w is 1 iseffective in preventing a decrease in specific resistance that is causedby heating under air because it has a large volatility. The compound (6)where w is 7 is effective in maintaining a large voltage holding ratioat room temperature and also at a high temperature even after the devicewas used for a long time, because it has a small volatility. A desirableratio of the antioxidant is 50 ppm or more for achieving its effect andis 600 ppm or less for avoiding a decrease in the maximum temperature oravoiding an increase in the minimum temperature. Amore desirable ratiois in the range of 100 ppm to 300 ppm.

Desirable examples of the ultraviolet light absorber include abenzophenone derivative, a benzoate derivative and a triazolederivative. A light stabilizer such as an amine having steric hindranceis also desirable. A desirable ratio of the ultraviolet light absorberor the light stabilizer is 50 ppm or more for achieving its effect andis 10,000 ppm or less for avoiding a decrease in the maximum temperatureor avoiding an increase in the minimum temperature. A more desirableratio is in the range of 100 ppm to 10,000 ppm.

A dichroic dye such as an azo dye or an anthraquinone dye is mixed withthe composition for adjusting to a device having a guest host (GH) mode.A desirable ratio of the coloring matter is in the range of 0.01% byweight to 10% by weight. An antifoaming agent such as dimethyl siliconeoil or methyl phenyl silicone oil is mixed with the composition forpreventing foam formation. A desirable ratio of the antifoaming agent is1 ppm or more for achieving its effect and is 1,000 ppm or less foravoiding a poor display. A more desirable ratio is in the range of 1 ppmto 500 ppm.

A polymerizable compound is mixed with the composition for adjusting toa device having a polymer sustained alignment (PSA) mode. Desirableexamples of the polymerizable compound include compounds having apolymerizable group, such as acrylates, methacrylates, vinyl compounds,vinyloxy compounds, propenyl ethers, epoxy compounds (oxiranes,oxetanes) and vinyl ketones. Especially desirable examples of thepolymerizable compound are acrylate derivatives or methacrylatederivatives. A desirable ratio of the polymerizable compound is 0.05% byweight or more for achieving its effect and is 10% by weight or less foravoiding a poor display. A more desirable ratio is in the range of 0.1%by weight to 2% by weight. The polymerizable compound is polymerized onirradiation with ultraviolet light or the like, preferably in thepresence of a suitable initiator such as a photopolymerizationinitiator. Suitable conditions for polymerization, suitable types of theinitiator and suitable amounts thereof are known to a person skilled inthe art and are described in the literature. For example, Irgacure 651(registered trademark), Irgacure 184 (registered trademark) or Darocure1173 (registered trademark) (Ciba Japan K.K.), each of which is aphotopolymerization initiator, is suitable for radical polymerization.The polymerizable compound includes the photopolymerization initiatorpreferably in the range of 0.1% by weight to 5% by weight and mostpreferably in the range of 1% by weight to 3% by weight.

Seventh, methods for synthesizing the component compounds will beexplained. These compounds can be synthesized by known methods. Thesynthetic methods will be exemplified as follows. The compound (1-1-1)is prepared by the method described in JP H10-291945 A (1998). Thecompound (2-5-1) is prepared by the method described in JP 2000-008040 A(2000). The compound (3-1-1) is prepared by the method described in JPH04-030382 B (1992). The compound (3-4-1) is prepared by the methoddescribed in JP S57-165328 A (1982). The compound (4-1-1) is prepared bythe method described in JP 2000-053602 A (2000). An antioxidant iscommercially available. The compound where w is 1 in formula (6) isavailable from Sigma-Aldrich Corporation. The compound (6) where w is 7,and so forth are synthesized according to the method described in U.S.Pat. No. 3,660,505.

Compounds whose synthetic methods are not described above can beprepared according to the methods described in books such as OrganicSyntheses (John Wiley & Sons, Inc.), Organic Reactions (John Wiley &Sons, Inc.), Comprehensive Organic Synthesis (Pergamon Press), Newexperimental Chemistry Course (Shin Jikken Kagaku Kouza, in Japanese;Maruzen Co., Ltd.). The composition is prepared according to knownmethods using the compounds thus obtained. For example, the componentcompounds are mixed and dissolved each other by heating.

Last, use of the composition will be explained. Most of the compositionsof the invention have a minimum temperature of −10° C. or lower, amaximum temperature of 70° C. or higher, and an optical anisotropy inthe range of 0.07 to 0.20. A device containing this composition has alarge voltage holding ratio. The composition is suitable for an AMdevice. The composition is suitable especially for an AM device having atransmission type. The composition having an optical anisotropy in therange of 0.08 to 0.25 may be prepared by adjusting ratios of thecomponent compounds or by mixing with any other liquid crystal compound.The composition can be used as a composition having a nematic phase, oras an optically active composition by the addition of an opticallyactive compound.

The composition can be used for an AM device. It can also be used for aPM device. The composition can also be used for the AM device and the PMdevice having a mode such as PC, TN, STN, ECB, OCB, IPS, VA or PSA. Itis especially desirable to use the composition for the AM device havingthe IPS or VA mode. These devices may be of a reflection type, atransmission type or a semi-transmission type. It is desirable to usethe composition for a device having the transmission type. It can beused for an amorphous silicon-TFT device or a polycrystal silicon-TFTdevice. The composition is also usable for a nematic curvilinear alignedphase (NCAP) device prepared by microcapsulating the composition, andfor a polymer dispersed (PD) device in which a three-dimensionalnetwork-polymer is formed in the composition.

EXAMPLES

When a sample was a composition, it was measured as it was, and thevalue obtained was described here. When a sample was a compound, asample for measurement was prepared by mixing 15% by weight of thecompound and 85% by weight of mother liquid crystals. The characteristicvalues of the compound were calculated from values obtained bymeasurement, according to a method of extrapolation. That is:(extrapolated value)=[(measured value of a sample)−0.85×(measured valueof mother liquid crystals)]/0.15. When a smectic phase (or crystals)separated out in this ratio at 25° C., the ratio of the compound to themother liquid crystals was changed step by step in the order of (10% byweight/90% by weight), (5% by weight/95% by weight) and (1% byweight/99% by weight). Values of the maximum temperature, the opticalanisotropy, the viscosity and the dielectric anisotropy with regard tothe compound were obtained by this extrapolation method.

The components of the mother liquid crystals were as follows.

Characteristics were measured according to the following methods. Mostmethods are described in the Standards of Electronic IndustriesAssociation of Japan, EIAJ•ED-2521 A or those with some modifications.

Maximum Temperature of a Nematic Phase (NI; ° C.): A sample was placedon a hot plate in a melting point apparatus equipped with a polarizingmicroscope and was heated at the rate of 1° C. per minute. Thetemperature was measured when part of the sample began to change from anematic phase to an isotropic liquid. A higher limit of the temperaturerange of a nematic phase may be abbreviated to “the maximumtemperature.”

Minimum Temperature of a Nematic Phase (Tc; ° C.): A sample having anematic phase was put in glass vials and then kept in freezers attemperatures of 0° C., −10° C., −20° C., −30° C. and −40° C. for 10days, and then the liquid crystal phases were observed. For example,when the sample maintained the nematic phase at −20° C. and changed tocrystals or a smectic phase at −30° C., Tc was expressed as ≦−20° C. Alower limit of the temperature range of a nematic phase may beabbreviated to “the minimum temperature.”

Viscosity (bulk viscosity; η; measured at 20° C.; mPa·s): Viscosity wasmeasured by use of an E-type viscometer.

Optical Anisotropy (refractive index anisotropy; Δn; measured at 25°C.): Measurement was carried out by use of an Abbe refractometer with apolarizing plate mounted on the ocular, using light at a wavelength of589 nanometers. The surface of the main prism was rubbed in onedirection, and then a sample was dropped on the main prism. A refractiveindex (nil) was measured when the direction of polarized light wasparallel to that of the rubbing. A refractive index (n1) was measuredwhen the direction of polarized light was perpendicular to that of therubbing. The value of optical anisotropy was calculated from theequation: Δn=n∥−n⊥.

Dielectric Anisotropy (As; measured at 25° C.): The value of dielectricanisotropy was calculated from the equation: Δ∈=∈∥−∈⊥. Dielectricconstants (∈∥ and ∈⊥) were measured as follows.

1) Measurement of a dielectric constant (∈∥): A solution ofoctadecyltriethoxysilane (0.16 mL) in ethanol (20 mL) was applied to athoroughly cleaned glass substrate. The glass substrate was rotated witha spinner, and then heated at 150° C. for one hour. A sample was pouredinto a VA device in which the distance between the two glass substrates(cell gap) was 4 micrometers, and then the device was sealed with anadhesive curable on irradiation with ultraviolet light. Sine waves (0.5V, 1 kHz) were applied to the device, and a dielectric constant (∈∥) inthe major axis direction of liquid crystal molecules was measured after2 seconds.2) Measurement of a dielectric constant (∈⊥): A polyimide solution wasapplied to a thoroughly cleaned glass substrate. The glass substrate wasburned, and then the resulting alignment film was subjected to rubbingtreatment. A sample was poured into a TN device in which the distancebetween the two glass substrates (cell gap) was 9 micrometers and thetwist angle was 80 degrees. Sine waves (0.5V, 1 kHz) were applied to thedevice, and a dielectric constant (∈⊥) in the minor axis direction ofliquid crystal molecules was measured after 2 seconds.

Threshold Voltage (Vth; measured at 25° C.; V): Measurement was carriedout with an LCD evaluation system Model LCD-5100 made by OtsukaElectronics Co., Ltd. The light source was a halogen lamp. A sample waspoured into a VA device having a normally black mode, in which thedistance between the two glass substrates (cell gap) was 4 micrometersand the rubbing direction was antiparallel, and then the device wassealed with an adhesive curable on irradiation with ultraviolet light.Voltage to be applied to the device (60 Hz, rectangular waves) wasstepwise increased in 0.02 V increments from 0 V up to 20 V. During theincrease, the device was irradiated with light in the perpendiculardirection, and the amount of light passing through the device wasmeasured. A voltage-transmittance curve was prepared, in which themaximum amount of light corresponded to 100% transmittance and theminimum amount of light corresponded to 0% transmittance. The thresholdvoltage was voltage at 10% transmittance.

Voltage Holding Ratio (VHR-1; measured at 25° C.; %): A TN device usedfor measurement had a polyimide-alignment film, and the distance betweenthe two glass substrates (cell gap) was 5 micrometers. A sample waspoured into the device, and then the device was sealed with aUV-polymerizable adhesive. A pulse voltage (60 microseconds at 5 V) wasapplied to the TN device and the device was charged. A decreasingvoltage was measured for 16.7 milliseconds with a high-speed voltmeter,and the area A between the voltage curve and the horizontal axis in aunit cycle was obtained. The area B was an area without the decrease.The voltage holding ratio was the percentage of the area A to the areaB.

Voltage Holding Ratio (VHR-2; measured at 80° C.; %): A TN device usedfor measurement had a polyimide-alignment film, and the distance betweenthe two glass substrates (cell gap) was 5 micrometer. A sample waspoured into the device, and then the device was sealed with aUV-polymerizable adhesive. A pulse voltage (60 microseconds at 5 V) wasapplied to the TN device and the device was charged. A decreasingvoltage was measured for 16.7 milliseconds with a high-speed voltmeterand the area A between the voltage curve and the horizontal axis in aunit cycle was obtained. The area B was an area without the decrease.The voltage holding ratio was a percentage of the area A to the area B.

Voltage Holding Ratio (VHR-3; measured at 25° C.; %): The stability toultraviolet light was evaluated by measuring a voltage holding ratioafter irradiation with ultraviolet light. A composition having a largeVHR-3 has a high stability to ultraviolet light. A TN device used formeasurement had a polyimide-alignment film and the cell gap was 5micrometers. A sample was poured into this device, and then the devicewas irradiated with light for 20 minutes. The light source was an ultrahigh-pressure mercury lamp USH-500D (produced by Ushio, Inc.), and thedistance between the device and the light source was 20 centimeters. Inthe measurement of VHR-3, a decreasing voltage was measured for 16.7milliseconds. The value of VHR-3 is preferably 90% or more, and morepreferably 95% or more.

Voltage Holding Ratio (VHR-4; measured at 25° C.; %): A TN device intowhich a sample was poured was heated in a constant-temperature bath at80° C. for 500 hours, and then the stability to heat was evaluated bymeasuring the voltage holding ratio. A composition having a large VHR-4has a high stability to heat. In the measurement of VHR-4, a decreasingvoltage was measured for 16.7 milliseconds.

Response Time (τ; measured at 25° C.; millisecond): Measurement wascarried out with an LCD evaluation system Model LCD-5100 made by OtsukaElectronics Co., Ltd. The light source was a halogen lamp. The low-passfilter was set at 5 kHz. A sample was poured into a VA device having anormally black mode, in which the cell gap between the two glasssubstrates was 4 micrometers, and the rubbing direction wasantiparallel, and then the device was sealed with a UV curable adhesive.Rectangular waves (60 Hz, 10 V, 0.5 second) were applied to the device.The device was simultaneously irradiated with light in the perpendiculardirection, and the amount of light passing through the device wasmeasured. The maximum amount of light corresponded to 100%transmittance, and the minimum amount of light corresponded to 0%transmittance. The response time was the period of time required for thechange from 90% to 10% transmittance (fall time; millisecond).

Specific Resistance (ρ; measured at 25° C.; Ωcm): A sample of 1.0milliliter was poured into a vessel equipped with electrodes. DC voltage(10 V) was applied to the vessel, and the DC current was measured after10 seconds. The specific resistance was calculated from the followingequation. (specific resistance)=[(voltage)×(electric capacity ofvessel)]/[(DC current)×(dielectric constant in vacuum)].

Gas Chromatographic Analysis: A gas chromatograph Model GC-14B made byShimadzu Corporation was used for measurement. The carrier gas washelium (2 milliliters per minute). The sample injector and the detector(FID) were set to 280° C. and 300° C., respectively. A capillary columnDB-1 (length 30 meters, bore 0.32 millimeter, film thickness 0.25micrometer, dimethylpolysiloxane as the stationary phase, non-polar)made by Agilent Technologies, Inc. was used for the separation ofcomponent compounds. After the column had been kept at 200° C. for 2minutes, it was further heated to 280° C. at the rate of 5° C. perminute. A sample was dissolved in acetone (0.1% by weight), and 1microliter of the solution was injected into the sample injector. Arecorder used was a Model C-R5A Chromatopac Integrator made by ShimadzuCorporation or its equivalent. The resulting gas chromatogram showed theretention time of peaks and the peak areas corresponding to thecomponent compounds.

Solvents for diluting the sample may also be chloroform, hexane and soforth. The following capillary columns may also be used in order toseparate the component compounds: HP-1 made by Agilent Technologies Inc.(length 30 meters, bore 0.32 millimeter, film thickness 0.25micrometer), Rtx-1 made by Restek Corporation (length 30 meters, bore0.32 millimeter, film thickness 0.25 micrometer), and BP-1 made by SGEInternational Pty. Ltd. (length 30 meters, bore 0.32 millimeter, filmthickness 0.25 micrometer). A capillary column CBP1-M50-025 (length 50meters, bore 0.25 millimeter, film thickness 0.25 micrometer) made byShimadzu Corporation may also be used for the purpose of avoiding anoverlap of peaks of the compounds.

The ratio of the liquid crystal compounds included in the compositionmay be calculated according to the following method. The liquid crystalcompounds are detected by use of a gas chromatograph. The ratio of peakareas in the gas chromatogram corresponds to the ratio (molar ratio) ofthe liquid crystal compounds. When the capillary columns described aboveare used, the correction coefficient of respective liquid crystalcompounds may be regarded as 1 (one). Accordingly, the ratio (percentageby weight) of the liquid crystal compound can be calculated from theratio of peak areas.

The invention will be explained in detail by way of Examples. Theinvention is not limited by Examples described below. The compoundsdescribed in Comparative Examples and Examples were expressed as symbolsaccording to the definition in the following Table 3. In Table 3, theconfiguration of 1,4-cyclohexylene is trans. A parenthesized number nextto the symbolized compound in Example corresponds to the number of acompound. The symbol (−) means any other liquid crystal compound. Ratios(percentage) of liquid crystal compounds mean the percentages by weight(% by weight) based on the total weight of the liquid crystalcomposition. The liquid crystal composition further includes animpurity. Last, the characteristic values of the composition aresummarized.

TABLE 3 Method of Description of Compound using Symbols. R-(A₁)-Z₁- . .. -Z_(n)-(A_(n))-R′ 1) Left Terminal Group R- Symbol C_(n)H_(2n+1)- n-C_(n)H_(2n+1)O— nO- C_(m)H_(2m+1)OC_(n)H_(2n)— mOn- CH₂═CH— V-C_(n)H_(2n+1)—CH═CH— nV- CH₂═CH—C_(n)H_(2n)— Vn-C_(m)H_(2m+1)—CH═CH—C_(n)H_(2n)— mVn- CF₂═CH— VFF- CF₂═CH—C_(n)H_(2n)—VFFn- 2) Right Terminal Group - R′ Symbol —C_(n)H_(2n+1) -n—OC_(n)H_(2n+1) -On —CH═CH₂ -V —CH═CH—C_(n)H_(2n+1) -Vn—C_(n)H_(2n)—CH═CH₂ -nV —CH═CF₂ -VFF —COOCH₃ -EMe 3) Bonding group-Z_(n)- Symbol —OC_(n)H_(2n)O— OnO —C_(n)H_(2n)— n —COO— E —CH═CH— V—CH₂O— 1O —OCH₂— O1 —SiH₂— Si 4) Ring Structure -A_(n)- Symbol

H

ch

B

B(2F)

B(3F)

B(2F,3F)

B(2F,3CL)

B(2CL,3F)

dh

Dh

B(2F,3F,6Me)

B(2F,3Cl,6Me)

Cro(7F,8H)

B(2Cl,3F,6Me) 5) Example of Description

Comparative Example 1

Example 7 was selected from the compositions disclosed in JP 2006-160857A. The basis of the selection was that the composition included thecompound (1-2-3), the compound (3-1-1), the compound (3-4-1) and thecompound (4-1-1-1), (4-1-4-1), (4-1-7-1) and the viscosity was thesmallest. This composition was prepared, and measured by the methoddescribed above. The components and characteristics of the compositionwere as follows:

3-HH1OB(2F,3F,6Me)-O2 (1-2-3) 8% 5-HH1OB(2F,3F,6Me)-O2 (1-2-3) 8% 2-HH-5(3-1-1) 5% 3-HH-4 (3-1-1) 15%  3-HH-5 (3-1-1) 8% 3-HHB-1 (3-4-1) 5%3-HHB-O1 (3-4-1) 3% 3-HHB-3 (3-4-1) 5% 3-HH1OH-3 (3) 3% 3-HB(2F,3F)-O2(4-1-1-1) 10%  3-HB(2F,3F)-O4 (4-1-1-1) 10%  3-HHB(2F,3F)-O2 (4-1-4-1)5% 3-HBB(2F,3F)-O2 (4-1-7-1) 5% 3-HB(3F)B(2F,3F)-O2 (—) 5%3-HB(2F)B(2F,3F)-O2 (—) 5% NI = 88.1° C.; Tc ≦ −20° C.; Δn = 0.078; η =24.7 mPa·s; Δε = −3.4; VHR-1 = 99.4%.

Example 1

3-HH1OB(2F,3F,6Me)-O2 (1-2-3) 8% 5-HH1OB(2F,3F,6Me)-O2 (1-2-3) 7%2-DhHB(2F,3F)-O2 (2-4-1) 4% 3-DhHB(2F,3F)-O2 (2-4-1) 5% 5-DhHB(2F,3F)-O2(2-4-1) 5% 3-HDhB(2F,3F)-O2 (2-5-1) 7% 5-HDhB(2F,3F)-O2 (2-5-1) 6%2-HH-3 (3-1-1) 10%  2-HH-5 (3-1-1) 10%  3-HH-O1 (3-1-1) 8% 5-HH-V(3-1-1) 18%  3-HHB-1 (3-4-1) 3% 3-HHB-3 (3-4-1) 4% 1O1-HBBH-5 (—) 5% NI= 90.9° C.; Tc ≦ −20° C.; Δn = 0.072; η = 22.4 mPa·s; Δε = −2.3; VHR-1 =99.4%; VHR-2 = 98.1%; VHR-3 = 97.9%.

Example 2

3-HH2B(2F,3F,6Me)-O2 (1-2-2) 7% 5-HH2B(2F,3F,6Me)-O2 (1-2-2) 8%3-HH1OB(2F,3F,6Me)-O2 (1-2-3) 6% 5-HH1OB(2F,3F,6Me)-O2 (1-2-3) 6%3-DhHB(2F,3F)-O2 (2-4-1) 4% 4-DhHB(2F,3F)-O2 (2-4-1) 3% 5-DhHB(2F,3F)-O2(2-4-1) 4% 3-HDhB(2F,3F)-O2 (2-5-1) 5% 5-HDhB(2F,3F)-O2 (2-5-1) 7%3-HH-4 (3-1-1) 5% 3-HH-5 (3-1-1) 5% 3-HH-V (3-1-1) 30%  3-HH-V1 (3-1-1)7% 1O1-HBBH-4 (—) 3% NI = 90.5° C.; Tc ≦ −20° C.; Δn = 0.075; η = 22.0mPa·s; Δε = −2.5; VHR-1 = 99.4%; VHR-2 = 98.0%; VHR-3 = 97.8%.

Example 3

3-H2B(2F,3F,6Me)-O2 (1-1-2) 7% 5-H2B(2F,3F,6Me)-O2 (1-1-2) 7%3-HH1OB(2F,3F,6Me)-O2 (1-2-3) 7% 2-DhHB(2F,3F)-O2 (2-4-1) 3%3-DhHB(2F,3F)-O2 (2-4-1) 5% 5-DhHB(2F,3F)-O2 (2-4-1) 5% 3-HDhB(2F,3F)-O2(2-5-1) 6% 5-HDhB(2F,3F)-O2 (2-5-1) 5% 2-HH-3 (3-1-1) 15%  3-HH-5(3-1-1) 3% 3-HH-V (3-1-1) 7% 3-HHB-1 (3-4-1) 5% 3-HHB-O1 (3-4-1) 5%V-HHB-1 (3-4-1) 10%  V2-HHB-1 (3-4-1) 10%  NI = 90.6° C.; Tc ≦ −20° C;Δn = 0.082; η = 22.5 mPa·s; Δε = −2.3; VHR-1 = 99.6%; VHR-2 = 98.1%;VHR-3 = 98.0%.

Example 4

3-H1OB(2F,3F,6Me)-O2 (1-1-3) 8% 5-H1OB(2F,3F,6Me)-O2 (1-1-3) 8%3-HH1OB(2F,3F,6Me)-O2 (1-2-3) 5% 5-HH1OB(2F,3F,6Me)-O2 (1-2-3) 5%2-DhHB(2F,3F)-O2 (2-4-1) 5% 3-DhHB(2F,3F)-O2 (2-4-1) 5% 5-HDhB(2F,3F)-O2(2-5-1) 5% 3-DhBB(2F,3F)-O2 (2-6-1) 3% 2-HH-3 (3-1-1) 19%  3-HH-5(3-1-1) 8% 3-HH-V (3-1-1) 3% 3-HH-V1 (3-1-1) 8% 3-HHB-O1 (3-4-1) 2%2-BB(3F)B-3 (3-6-1) 3% 5-HBB(3F)B-2 (3-12-1) 6% 5-HBB(3F)B-3 (3-12-1) 7%NI = 90.4° C.; Tc ≦ −20° C.; Δn = 0.099; η = 22.7 mPa·s; Δε = −2.3.

Example 5

5-H1OB(2F,3F,6Me)-O2 (1-1-3) 8% 3-HH1OB(2F,3F,6Me)-O2 (1-2-3) 5%5-HH1OB(2F,3F,6Me)-O2 (1-2-3) 5% 3-HB2B(2F,3F,6Me)-O2 (1-2-5) 5%5-DhB(2F,3F)-O2 (2-1-1) 7% 3-DhHB(2F,3F)-O2 (2-4-1) 4% 5-DhHB(2F,3F)-O2(2-4-1) 5% 3-HDhB(2F,3F)-O2 (2-5-1) 5% 2-HH-3 (3-1-1) 5% 3-HH-V (3-1-1)20%  5-HB-O2 (3-2-1) 3% V2-BB-1 (3-3-1) 3% 3-HHB-1 (3-4-1) 7% 3-HHB-O1(3-4-1) 4% 1-BB(3F)B-2V (3-6-1) 3% 3-HHEH-5 (3-7-1) 3% 3-HHEBH-3 (3-8-1)5% 5-HBB(3F)B-2 (3-12-1) 3% NI = 90.1° C.; Tc ≦ −20° C.; Δn = 0.093; η =22.7 mPa·s; Δε = −2.3.

Example 6

3-H1OB(2F,3F,6Me)-O2 (1-1-3) 10%  3-HH1OB(2F,3F,6Me)-O2 (1-2-3) 5%3-Dh2B(2F,3F)-O4 (2-2-1) 5% 3-DhHB(2F,3F)-O2 (2-4-1) 3% V-DhHB(2F,3F)-O2(2-4-1) 3% 3-HDhB(2F,3F)-O2 (2-5-1) 5% 2-HH-5 (3-1-1) 9% 3-HH-V (3-1-1)20%  3-HHB-1 (3-4-1) 5% 3-HHB-3 (3-4-1) 5% 3-HHEBH-5 (3-8-1) 3%5-HBB(3F)B-3 (3-12-1) 8% V-HB(2F,3F)-O2 (4-1-1-1) 5% 3-HBB(2F,3F)-O2(4-1-7-1) 7% V2-HBB(2F,3F)-O2 (4-1-7-1) 7% NI = 92.4° C.; Tc ≦ −20° C.;Δn = 0.099; η = 21.4 mPa·s; Δε = −2.5.

Example 7

5-H1OB(2F,3F,6Me)-O2 (1-1-3) 6% 3-HH1OB(2F,3F,6Me)-O2 (1-2-3) 4%5-HH1OB(2F,3F,6Me)-O2 (1-2-3) 5% 3-DhB(2F,3F)-O2 (2-1-1) 5%3-DhHB(2F,3F)-O2 (2-4-1) 5% 5-HDhB(2F,3F)-O2 (2-5-1) 3% 2-HH-3 (3-1-1)10%  3-HH-V (3-1-1) 14%  V2-HHB-1 (3-4-1) 5% 1V-HBB-2 (3-5-1) 3%V2-BB(3F)B-1 (3-6-1) 3% 3-HHEBH-3 (3-8-1) 3% 5-HBB(3F)B-3 (3-12-1) 3%V-HB(2F,3F)-O2 (4-1-1-1) 5% 5-H2B(2F,3F)-O2 (4-1-2-1) 5% 5-HHB(2F,3F)-O2(4-1-4-1) 5% 3-HHB(2F,3F)-1 (4-1-4-1) 3% 3-HH2B(2F,3F)-O2 (4-1-5-1) 5%3-HH1OB(2F,3F)-O2 (4-1-6-1) 5% 5-HHB(2F,3CL)-O2 (4-1-8-1) 3% NI = 92.5°C.; Tc ≦ −20° C.; Δn = 0.092; η = 21.9 mPa·s; Δε = −3.0.

Example 8

3-H2B(2F,3F,6Me)-O2 (1-1-2) 7% 3-H1OB(2F,3F,6Me)-O2 (1-1-3) 5%5-HH1OB(2F,3F,6Me)-O2 (1-2-3) 5% 3-DhHB(2F,3F)-O2 (2-4-1) 5%3-HDhB(2F,3F)-O2 (2-5-1) 5% 2-HH-3 (3-1-1) 18%  3-HH-V1 (3-1-1) 5%5-HB-3 (3-2-1) 3% 3-HB-O1 (3-2-1) 3% V2-BB-1 (3-3-1) 3% 3-HHB-3 (3-4-1)5% V2-HHB-1 (3-4-1) 5% 3-HBB-2 (3-5-1) 3% 3-HHEBH-3 (3-8-1) 5% 3-HBBH-3(3-9-1) 3% 3-HB(3F)BH-3 (3-11-1) 3% V-HB(2F,3F)-O4 (4-1-1-1) 5%5-HH1OB(2F,3F)-O2 (4-1-6-1) 3% 3-HBB(2F,3F)-O2 (4-1-7-1) 3%V-HBB(2F,3F)-O2 (4-1-7-1) 3% 5-HBB(2F,3CL)-O2 (4-1-9-1) 3% NI = 91.1°C.; Tc ≦ −20° C.; Δn = 0.094; η = 20.2 mPa·s; Δε = −2.3.

Example 9

3-H1OB(2F,3F,6Me)-O2 (1-1-3) 5% 5-HH1OB(2F,3F,6Me)-O2 (1-2-3) 5%3-dhBB(2F,3F)-O2 (2-7-1) 3% 4-dhBB(2F,3F)-O2 (2-7-1) 3% 5-dhBB(2F,3F)-O2(2-7-1) 3% 2-HH-3 (3-1-1) 11%  3-HH-V (3-1-1) 14%  V2-BB-1 (3-3-1) 5%V2-HHB-1 (3-4-1) 5% 2-BB(3F)B-3 (3-6-1) 3% 3-HHEBH-3 (3-8-1) 5%5-HB(2F,3F)-O2 (4-1-1-1) 3% V-HB(2F,3F)-O2 (4-1-1-1) 5% 5-HHB(2F,3F)-O2(4-1-4-1) 5% V2-HHB(2F,3F)-O2 (4-1-4-1) 5% 1V2-HHB(2F,3F)-O2 (4-1-4-1)3% 5-HBB(2F,3F)-O2 (4-1-7-1) 4% 5-HHB(2F,3CL)-O2 (4-1-8-1) 4%5-H1OCro(7F,8F)5 (4-2-2-1) 3% 3-HH1OCro(7F,8F)-5 (4-2-4-1) 3%2-BB(2F,3F)B-3 (—) 3% NI = 92.3° C.; Tc ≦ −20° C.; Δn = 0.102; η = 22.6mPa·s; Δε = −2.7.

Example 10

3-H1OB(2F,3F,6Me)-O2 (1-1-3) 5% 3-HH1OB(2F,3F,6Me)-O2 (1-2-3) 5%5-DhHB(2F,3F)-O2 (2-4-1) 3% V-HDhB(2F,3F)-O2 (2-5-1) 3% 2-HH-3 (3-1-1)5% 3-HH-V (3-1-1) 25%  3-HHB-O1 (3-4-1) 5% V2-HHB-1 (3-4-1) 5% 3-HHEBH-5(3-8-1) 5% 5-HBB(3F)B-2 (3-12-1) 3% V-HB(2F,3F)-O2 (4-1-1-1) 3%5-H2B(2F,3F)-O2 (4-1-2-1) 4% 2-H1OB(2F,3F)-O2 (4-1-3-1) 3%3-HHB(2F,3F)-O2 (4-1-4-1) 3% V-HHB(2F,3F)-O2 (4-1-4-1) 3%5-HH2B(2F,3F)-O2 (4-1-5-1) 5% 5-HBB(2F,3F)-O2 (4-1-7-1) 5%4O-Cro(7F,8F)H-3 (4-2) 5% 3-HH1OCro(7F,8F)-5 (4-2-4-1) 5% NI = 91.7° C.;Tc ≦ −20° C.; Δn = 0.085; η = 22.2 mPa·s; Δε = −2.8.

Example 11

3-H1OB(2F,3F,6Me)-O2 (1-1-3) 10%  3-HH2B(2F,3CL,6Me)-O2 (1-2-2) 5%3-HH1OB(2F,3F,6Me)-O2 (1-2-3) 5% 5-HH1OB(2F,3F,6Me)-O2 (1-2-3) 5%3-Dh2B(2F,3F)-O4 (2-2-1) 5% 5-HDhB(2F,3F)-O2 (2-5-1) 3% 2-HH-3 (3-1-1)6% 3-HH-V (3-1-1) 20%  V2-BB-1 (3-3-1) 3% 3-HHB-O1 (3-4-1) 5% 3-HBB-2(3-5-1) 5% 3-HBBH-3 (3-9-1) 3% 5-HBB(3F)B-2 (3-12-1) 5% 5-HBB(3F)B-3(3-12-1) 3% V-HB(2F,3F)-O4 (4-1-1-1) 5% 3-HBB(2F,3F)-O2 (4-1-7-1) 5%5-HBB(2F,3F)-O2 (4-1-7-1) 4% 5-HBB(2F,3CL)-O2 (4-1-9-1) 3% NI = 90.3°C.; Tc ≦ −20° C.; Δn = 0.104; η = 22.7 mPa·s; Δε = −2.4.

Example 12

3-H2B(2F,3F,6Me)-O2 (1-1-2) 8% 3-HH1OB(2CL,3F,6Me)-O2 (1-2-3) 5%5-DhB(2F,3F)-O2 (2-1-1) 5% 3-DhHB(2F,3F)-O2 (2-4-1) 5% 5-HDhB(2F,3F)-O2(2-5-1) 5% 2-HH-3 (3-1-1) 10%  3-HH-V (3-1-1) 20%  3-HHB-1 (3-4-1) 10% 3-HHB-O1 (3-4-1) 5% 5-HBB(3F)B-3 (3-12-1) 5% 3-HB(3F)HH-5 (3-10-1) 3%V-HB(2F,3F)-O2 (4-1-1-1) 5% 3-HBB(2F,3F)-O2 (4-1-7-1) 7%V2-HBB(2F,3F)-O2 (4-1-7-1) 7% NI = 91.9° C.; Tc ≦ −20° C.; Δn = 0.095; η= 22.6 mPa·s; Δε = −2.4.

The compositions in Example 1 to Example 12 have a higher maximumtemperature and a smaller viscosity than those in Comparative Example 1.Thus, the liquid crystal composition of the invention is so muchsuperior to the liquid crystal compositions disclosed in the patentdocument No. 1.

INDUSTRIAL APPLICABILITY

The invention provides a liquid crystal composition that satisfies atleast one of characteristics such as a high maximum temperature of anematic phase, a low minimum temperature of a nematic phase, a smallviscosity, a suitable optical anisotropy, a large negative dielectricanisotropy, a large specific resistance, a high stability to ultravioletlight and a high stability to heat, or that is suitably balancedregarding at least two of the characteristics. A liquid crystal displaydevice containing such a composition becomes an AM device that has ashort response time, a large voltage holding ratio, a large contrastratio, a long service life and so forth, and thus it can be used for aliquid crystal projector, a liquid crystal television and so forth.

1. A liquid crystal composition that includes at least one compound selected from the group of compounds represented by formula (1) as a first component and at least one compound selected from the group of compounds represented by formula (2) as a second component:

wherein R¹, R², R³ and R⁴ are independently alkyl having 1 to 12 carbons, alkoxy having 1 to 12 carbons, alkenyl having 2 to 12 carbons, alkenyloxy having 2 to 11 carbons, or alkenyl having 2 to 12 carbons in which arbitrary hydrogen is replaced by fluorine; ring A and ring B are each independently 1,4-cyclohexylene, 1,4-phenylene, 2-fluoro-1,4-phenylene, or 3-fluoro-1,4-phenylene; ring C is independently

at least one of ring C is

X¹, X², X³ and X⁴ are independently fluorine or chlorine; Z¹ and Z² are independently a single bond, ethylene, methyleneoxy or carbonyloxy; and m is 0, 1 or 2; n is 1 or
 2. 2. The liquid crystal composition according to claim 1, wherein the first component is at least one compound selected from the group of compounds represented by formula (1-1) and formula (1-2):

wherein R¹ and R² are independently alkyl having 1 to 12 carbons, alkoxy having 1 to 12 carbons, alkenyl having 2 to 12 carbons, alkenyloxy having 2 to 11 carbons, or alkenyl having 2 to 12 carbons in which arbitrary hydrogen is replaced by fluorine; ring B is independently 1,4-cyclohexylene, 1,4-phenylene, 2-fluoro-1,4-phenylene, or 3-fluoro-1,4-phenylene; X¹ and X² are independently fluorine or chlorine; Z³ is independently a single bond, ethylene or methyleneoxy.
 3. The liquid crystal composition according to claim 2, wherein the first component is at least one compound selected from the group of compounds represented by formula (1-2).
 4. The liquid crystal composition according to claim 2, wherein the first component is a mixture of at least one compound selected from the group of compounds represented by formula (1-1) and at least one compound selected from the group of compounds represented by formula (1-2).
 5. The liquid crystal composition according to claim 1, wherein the second component is at least one compound selected from the group of compounds represented by formula (2-1) to formula (2-7):

wherein R³ and R⁴ are independently alkyl having 1 to 12 carbons, alkoxy having 1 to 12 carbons, alkenyl having 2 to 12 carbons, alkenyloxy having 2 to 11 carbons, or alkenyl having 2 to 12 carbons in which arbitrary hydrogen is replaced by fluorine.
 6. The liquid crystal composition according to claim 5, wherein the second component is at least one compound selected from the group of compounds represented by formula (2-1) to formula (2-3).
 7. The liquid crystal composition according to claim 5, wherein the second component is at least one compound selected from the group of compounds represented by formula (2-4) to formula (2-7).
 8. The liquid crystal composition according to claim 1, wherein the ratio of the first component is in the range of 5% by weight to 70% by weight and the ratio of the second component is in the range of 5% by weight to 60% by weight, based on the total weight of the liquid crystal composition.
 9. The liquid crystal composition according to claim 1, further including at least one compound selected from the group of compounds represented by formula (3) as a third component:

wherein R⁵ and R⁶ are independently alkyl having 1 to 12 carbons, alkoxy having 1 to 12 carbons, alkenyl having 2 to 12 carbons, or alkenyl having 2 to 12 carbons in which arbitrary hydrogen is replaced by fluorine; ring D and the ring E are independently 1,4-cyclohexylene, 1,4-phenylene, 2-fluoro-1,4-phenylene or 3-fluoro-1,4-phenylene; Z⁴ is independently a single bond, ethylene, methyleneoxy or carbonyloxy; and p is 1, 2 or
 3. 10. The liquid crystal composition according to claim 9, wherein the third component is at least one compound selected from the group of compounds represented by formula (3-1) to formula (3-12):

wherein R⁵ and R⁶ are independently alkyl having 1 to 12 carbons, alkoxy having 1 to 12 carbons, alkenyl having 2 to 12 carbons, or alkenyl having 2 to 12 carbons in which arbitrary hydrogen is replaced by fluorine.
 11. The liquid crystal composition according to claim 10, wherein the third component is at least one compound selected from the group of compounds represented by formula (3-1).
 12. The liquid crystal composition according to claim 10, wherein the third component is a mixture of at least one compound selected from the group of compounds represented by formula (3-1) and at least one compound selected from the group of compounds represented by formula (3-4).
 13. The liquid crystal composition according to claim 10, wherein the third component is a mixture of at least one compound selected from the group of compounds represented by formula (3-6) and at least one compound selected from the group of compounds represented by formula (3-12).
 14. The liquid crystal composition according to claim 9, wherein the ratio of the third component is in the range of 10% by weight to 75% by weight based on the total weight of the liquid crystal composition.
 15. The liquid crystal composition according to claim 1, further including at least one compound selected from the group of compounds represented by formula (4-1) and (4-2) as a fourth component:

wherein R⁷ and R⁸ are independently alkyl having 1 to 12 carbons, alkoxy having 1 to 12 carbons, alkenyl having 2 to 12 carbons, or alkenyl having 2 to 12 carbons in which arbitrary hydrogen is replaced by fluorine; the ring F and ring G are each independently 1,4-cyclohexylene or 1,4-phenylene; Z⁵, Z⁶ and Z⁷ are each independently a single bond, ethylene, methyleneoxy or carbonyloxy; X⁵ and X⁶ are independently fluorine or chlorine; and q is 1, 2 or 3; r and s are each independently 0, 1, 2 or 3, and the sum of r and s is 3 or less.
 16. The liquid crystal composition according to claim 15, wherein the fourth component is at least one compound selected from the group of compounds represented by formula (4-1-1) to formula (4-1-9) and formula (4-2-1) to (4-2-5):

wherein R⁷ and R⁸ are independently alkyl having 1 to 12 carbons, alkoxy having 1 to 12 carbons, alkenyl having 2 to 12 carbons, or alkenyl having 2 to 12 carbons in which arbitrary hydrogen is replaced by fluorine. 17-18. (canceled)
 19. The liquid crystal composition according to claim 15, wherein the ratio of fourth component is 5% to 60% by weight based on the total weight of the liquid crystal composition.
 20. The liquid crystal composition according to claim 1, wherein the maximum temperature of a nematic phase is 70° C. or higher, the optical anisotropy (25° C.) at a wavelength of 589 nanometers is 0.08 or more, and the dielectric anisotropy (25° C.) at a frequency of 1 kHz is −2 or less.
 21. A liquid crystal display device containing the liquid crystal composition according to claim
 1. 22. The liquid crystal display device according to claim 21, wherein an operating mode of the liquid crystal display device is a VA mode, an IPS mode or a PSA mode, and a driving mode of the liquid crystal display device is an active matrix mode. 